Answer:
Add 3 to both sides of the equation
Solution:
The first step is to basically realize that all it's asking you to do is to find a way to make the expression on the left ([tex]x^2 - 8x + 13[/tex]) into an expression that is a perfect square. So what number should you add to both sides such that [tex]x^2 - 8x + (13 + j)[/tex] can be factored into [tex](x-p)^2[/tex] ? Well, we can approach it like this:
Since [tex](x-p)^2[/tex] can be turned into [tex]x^2 -2px + p^2[/tex], and our original form was [tex]x^2 - 8x + (13 + j)[/tex], we quickly realize that [tex]-2px = -8x[/tex]. From there, we can easily tell that [tex]p = 4[/tex]
Plug this into our last value [tex]p^2[/tex] to get 16. Therefore, if we compare this with our original equation again [tex]x^2 - 8x + (13 + j)[/tex], we notice that 13 + j = 16.
Thus, j = 3 for the last answer.
Add 3 to both sides of the equation.
Note: With more practice, you will quickly gain enough intuition to notice that [tex]x^2 - 8x + 13[/tex] is very close to [tex]x^2 - 8x + 16[/tex] which can be factored into [tex](x-4)^2[/tex]. But for now, the solution above will suffice. I hope this helps :))
